The invention relates to a bearing bridge for connecting main bearing seats of the crankshaft mounting arrangement of a combustion engine.
A bearing bridge of this kind is already known from German Patent 3,824,553.
An object on which the invention is based is to provide a bearing bridge of the type described above with which, on the one hand, a reduction in the power loss caused by the oil flowing back into the crank case striking the rotating drive parts and, on the other hand, a reduction in the oil ageing rate is achievable.
The object is achieved according to the invention by providing an arrangement wherein the bearing bridge forms a screen between the main bearing seats for the rotating drive parts of the combustion engine with respect to a crank case space.
By virtue of the design according to the invention of the bearing bridge, a space separated off with respect to the crank case space is created in which the rotating components of the combustion engine (crank pins, crank webs, big end and the counterweights) move. The oil flowing back out of the cylinders and the cylinder head thus passes back undisturbed into the crank case space without coming into contact with the rotating drive parts at all. The power loss caused by the so-called "splashing" is thereby reduced to a minimum. The screening off of the rotating drive parts also prevents intensive mixing of this oil which is flowing back with the very hot combustion gases passing via the piston rings into the crank case. As a result, the oil temperature remains at a relatively low temperature level. At the same time, the oil contamination caused by these gases is reduced. The rate of oil ageing and also the formation of sludge are thus markedly reduced.
Particularly effective screening off is achieved if the bearing bridge is designed as a dish-shaped casing, the dish rims of which extend into the transitional zone to the cylinder block and if, at the same time, the oil return bores for guiding back the oil from the cylinder head open between the bearing-bridge casing and the crank case wall into the crank case space.
In certain preferred embodiments it is provided that an oil run-off rib extending parallel to the longitudinal direction of the crankshaft and outwardly overlapping the dish rims is provided, with clearance on both sides at the crank case end of the cylinder block. This embodiment of the bearing bridge has the advantage that the oil scraped off by the piston rings and flowing back on the inner walls of the cylinder can drip off into the oil sump in controlled fashion between the bearing bridge casing and the crank case wall, i.e. likewise does not come into contact with the rotating drive parts.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.